Chris Kuklewicz wrote: > > *MyShow> main > > Hello" ""World #"[17,18,19]"!" > > I also think [4,5,6]" and "7" are ""cool""." > > The extra double quotes being what I am trying to avoid with MyShow
This is your only special case, a single list of a sigle type that is
different from other lists? To avoid undecidable, incoherent and other
nasty instances, just do what the Prelude does:
class MyShow t where
swim :: t -> String
swimList :: [t] -> String
swimList [] = "[]"
swimList xs = '[' : foldr1 (\x -> (swim x ++) . (',' :)) "]" xs
instance MyShow Char where
swim = (:[])
swimList = id
Untested, but you get the idea. It's pure Haskell 98. Heck, it's
almost Prelude.Show. It won't scale to more type constructors easily,
but you didn't ask for that ability, either ;-)
Udo.
--
"As far as Clinton supposedly cheating on his wife, what do people think
he's going to do? Be president of another country while he's president
of ours?"
-- Tom R., age 12
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